From: Zbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl>
Date: Mon, 11 Jan 2016 17:42:42 +0000 (-0500)
Subject: bus-kernel: reword assignment of dst_id in bus_message_setup_kmsg
X-Git-Tag: v229.1~1^2~65
X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?a=commitdiff_plain;h=75cbb152e09780f094d869c5d92d6815442f2900;hp=2647e847a11b64dd3757c88afbc1fbb2fb384a6f;p=elogind.git

bus-kernel: reword assignment of dst_id in bus_message_setup_kmsg

Setting of dst_id was based on interplay of two booleans,
making the logic hard to follow (for humans and compilers alike).
gcc was confused and emmitted a warning about an uninitialized
variable. Rework the code to make it obvious that dst_id is
set properly.
---

diff --git a/src/libelogind/sd-bus/bus-kernel.c b/src/libelogind/sd-bus/bus-kernel.c
index a4b3e7869..2391c0cd2 100644
--- a/src/libelogind/sd-bus/bus-kernel.c
+++ b/src/libelogind/sd-bus/bus-kernel.c
@@ -269,8 +269,8 @@ static int bus_message_setup_kmsg(sd_bus *b, sd_bus_message *m) {
         struct bus_body_part *part;
         struct kdbus_item *d;
         const char *destination;
-        bool well_known;
-        uint64_t unique;
+        bool well_known = false;
+        uint64_t dst_id;
         size_t sz, dl;
         unsigned i;
         int r;
@@ -287,13 +287,21 @@ static int bus_message_setup_kmsg(sd_bus *b, sd_bus_message *m) {
         destination = m->destination ?: m->destination_ptr;
 
         if (destination) {
-                r = bus_kernel_parse_unique_name(destination, &unique);
+                r = bus_kernel_parse_unique_name(destination, &dst_id);
                 if (r < 0)
                         return r;
-
-                well_known = r == 0;
+                if (r == 0) {
+                        well_known = true;
+
+                        /* verify_destination_id will usually be 0, which makes the kernel
+                         * driver only look at the provided well-known name. Otherwise,
+                         * the kernel will make sure the provided destination id matches
+                         * the owner of the provided well-known-name, and fail if they
+                         * differ. Currently, this is only needed for bus-proxyd. */
+                        dst_id = m->verify_destination_id;
+                }
         } else
-                well_known = false;
+                dst_id = KDBUS_DST_ID_BROADCAST;
 
         sz = offsetof(struct kdbus_msg, items);
 
@@ -331,15 +339,7 @@ static int bus_message_setup_kmsg(sd_bus *b, sd_bus_message *m) {
                 ((m->header->flags & BUS_MESSAGE_NO_AUTO_START) ? KDBUS_MSG_NO_AUTO_START : 0) |
                 ((m->header->type == SD_BUS_MESSAGE_SIGNAL) ? KDBUS_MSG_SIGNAL : 0);
 
-        if (well_known)
-                /* verify_destination_id will usually be 0, which makes the kernel driver only look
-                 * at the provided well-known name. Otherwise, the kernel will make sure the provided
-                 * destination id matches the owner of the provided weel-known-name, and fail if they
-                 * differ. Currently, this is only needed for bus-proxyd. */
-                m->kdbus->dst_id = m->verify_destination_id;
-        else
-                m->kdbus->dst_id = destination ? unique : KDBUS_DST_ID_BROADCAST;
-
+        m->kdbus->dst_id = dst_id;
         m->kdbus->payload_type = KDBUS_PAYLOAD_DBUS;
         m->kdbus->cookie = m->header->dbus2.cookie;
         m->kdbus->priority = m->priority;